Ergonomic writing instrument



FIG. 1 is a front perspective view of an ornamental design for an ergonomic writing instrument for right-handed use;

FIG. 2 is a front elevational view thereof;

FIG. 3 is a rear elevational view thereof;

FIG. 4 is a left side elevational view thereof;

FIG. 5 is a right side elevational view thereof;

FIG. 6 is a top elevational view thereof;

FIG. 7 is a bottom elevational view thereof;

FIG. 8 is a front perspective view of an ornamental design for an ergonomic writing instrument similar to that of FIGS. 1-17 but for left-handed use;

FIG. 9 is a front elevational view thereof;

FIG. 10 is a rear elevational view thereof;

FIG. 11 is a left side elevational view thereof;

FIG. 12 is a right side elevational view thereof;

FIG. 13 is a top elevational view thereof; and,

FIG. 14 is a bottom elevational view thereof.

All portions shown in broken lines are for illustrative purposes only and form no part of the claimed design. 

The ornamental design for an ergonomic writing instrument, as shown and described. 